1. Field of the Invention
The inventions disclosed and taught herein relate generally to solenoid valves; and more specifically relate to solenoid operated piloted valves.
2. Description of the Related Art
FIG. 1 shows a typical solenoid operated piloted diaphragm valve 10, shown in a closed position. In the closed position, process, or process control, fluid, or gas, enters an inlet port 12, but is prevented from exiting an outlet port 14. The fluid pushes against a diaphragm 16, which is held down in part by a solenoid operated plunger 18 and a closing spring 20. More specifically, the plunger 18 pushes a valve seal 22 of the diaphragm 16 against a valve seat 24, thereby isolating the inlet port 12 off from the outlet port. These parts are normally at least partially enclosed by a body 26.
An inlet pressure, of the process fluid, pushes against a first side 28 the diaphragm 16. If the force exerted by the inlet pressure is great enough to overcome the solenoid operated plunger 18 and/or closing spring 20, that inlet pressure could force the valve 10 to open without further provisions. This is often prevented by providing a bleed path 30 from the inlet port 12 to a second side 32 of the diaphragm 16, the second side 32 opposing the ports 12,14. Using the bleed path 30, more surface area of the second side 32 of the diaphragm 16 is exposed to the inlet pressure compared to the surface area that is exposed on the first side 28 of the diaphragm 16 at the inlet port 12. This difference in exposed surface area ensures that greater actual force is exerted against the second side 32 of the diaphragm 16 than is asserted against the first side 28 of the diaphragm 16, thereby holding the valve 10 closed.
Referring also to FIG. 2, when opening the valve 10 is desired, the solenoid operated plunger 18 is shifted away from the diaphragm 16, thereby exposing a pilot port 34 through the diaphragm 16. This allows the process fluid to escape from the second side 32 of the diaphragm 16 to the outlet port 14. To prevent the bleed path 30 from replenishing the process fluid as it escapes from the second side 32 of the diaphragm 16 to the outlet port 14 through the pilot port 34, the bleed path 30 often includes a restriction 36, and/or is otherwise sized to be more restrictive than the pilot port 34.
Therefore, as the process fluid escapes from the second side 32 of the diaphragm 16 to the outlet port 14, the bleed path 30 cannot replenish the process fluid fast enough, and thus the force it exerts on the second side 32 of the diaphragm 16 lessens. Referring also to FIG. 3, once the force on the second side 32 of the diaphragm 16 reaches, or becomes less than, the force the inlet pressure exerts on the first side 28 of the diaphragm 16 at the inlet port 12, the valve 10 opens and fully communicates the inlet port to the outlet port 14.
The inventions disclosed and taught herein are directed to an improved solenoid operated piloted diaphragm valve.